Question

A ball is thrown vertically upward, which is the positive direction, a little later it returns to its point of release, the ball is in the air for a total time of 2.1sec,what was its initial velocity

Answer 1

the ball stops rising when the time is half gone.

v-9.81t = 0
v = 9.81 * 2.1/2 = 10.3 m/s